4ms Shaped Dual EnvVCA User manual

Shaped Dual EnvVCA
4ms Company
User Manual 1.0 – November 15, 2022
The Shaped Dual EnvVCA is a dual analog envelope generator, waveshaper, slew limiter, and VCA.
Each of the two channels is identical and they can be used separately or together.
Shaped Dual EnvVCA features:
•Versatile linear, exponential, and logarithmic envelope generator/LFO
•Low-noise, low-distortion, DC-coupled linear VCAs
•Shape slider, CV jack and attenuverters for fading between Exponential, Linear, and Logarithmic
envelope shapes without changing envelope timing
•100% analog
•Sliders and range switches control Rise and Fall times from ~2ms (500Hz) to ~2 min.
•Time CV jack extends time range: ~400µs (2.5kHz) to ~1 hour.
•Independent attenuverters for Rise and Fall time
•Blue/Red lights indicate strength and polarity
•Cycle buttons for looping envelopes (LFO)
•Trigger input jack and switch for toggling between AR, ASR, and Cycle modes of triggering
•EOR/F (End of Rise/Fall) gate outputs can be used to chain and sequence events
•Env Level and Offset knobs scale and shift ENV output without changing VCA volume
•Audio In and Out jacks for passing audio or CV through the VCA
•VCA CV inputs to use VCAs independently from the envelopes
•VCA gain internally connected to envelope output when VCA CV jack is left unpatched
•Follow input jacks allow for slew limiting, envelope following/sidechaining, ADSR, and exotic
filtering effects
• Re-trig jumpers allow for re-triggering during rise phase
Cycle
AR
ASR
Cycle
AR
ASR
Rise Fall
Shaped Dual EnvVCA
TimeTime
Follow
VCA CVVCA CV
In
Audio BAudio A
Out
In
Out Lin 5VLin 5V
OR
Shape
Rise Fall
Slow
Fast
Med
Slow
Fast
Trig Cycle
Offset
Level
EOF
Fall
Rise
Shape Shape
Follow
ENV A ENV B
Shape
FallRise
Slow
Fast
Med
Slow
Fast
Trig
Cycle
Offset
Level
EOR A

Table of Contents
Setting up your Shaped Dual EnvVCA! "...................................................................3
Controls and Jacks! "................................................................................................3
Rise and Fall Time Ranges! "....................................................................................6
Patch: Making Notes! ".............................................................................................7
Making Notes (basic)! ".......................................................................................7
Making Notes in Stereo! "...................................................................................7
Synchronizing channels: Making Notes Using Triggers! "...................................8
Creating Stereo Motion! "....................................................................................8
Using a Keyboard or Sequencer! "......................................................................9
Patch: Waveshaping! "............................................................................................10
Modulating Waveshape! ".................................................................................10
Different Waveshapes for Rise and Fall! "...............................................................11
Log Rise with Expo Fall! ".................................................................................11
Any Combination of Shapes! "..........................................................................11
Patch: Modulating Time! ".......................................................................................12
Rapid Bursts! "..................................................................................................12
Ratcheting! "......................................................................................................12
Patch: Making an Oscillator and Synth Drums! "....................................................13
Making an Oscillator! "......................................................................................13
Making a Kick Drum! ".......................................................................................13
Making other Synth Drum sounds! ".................................................................14
Self-patching ideas! "..............................................................................................15
Frequency Modulation (FM)! "...........................................................................15
Chaotic FM! "....................................................................................................15
Utility Patches! "......................................................................................................15
Attenuator! "......................................................................................................15
Trigger Delay with Pulse Width control! "..........................................................15
Inverted Trigger Delay (With Pulse Width Control)! ".........................................15
DC generator (Manual CV)! ".............................................................................15
Creating Envelopes with Trig Jack and Switch, Cycle Button, and Follow Jack! ".16
Triggering with switch set to AR! "....................................................................16
Triggering with switch set to ASR! "..................................................................16
Triggering with RETRIG Jumper Off (Factory Default)! "...................................16
Triggering with RETRIG Jumper On! "...............................................................16
Cycle Button and Triggering with switch set to Cycle! "...................................16
Follow Jack with Gates! "..................................................................................17
Fundamentals of the Follow Jack! "........................................................................17
Audio filter! "......................................................................................................18
Portamento/glide! "...........................................................................................18
Sidechaining (Envelope Following)! "................................................................18
Using non-linear Shapes with Follow! "............................................................19
Creating ADSR Envelopes! "...................................................................................20
ADSR envelope! "..............................................................................................20
Table of Envelope Shapes! "...................................................................................22
Using Offset and Level Knobs! ".............................................................................23
RETRIG Jumper! "...................................................................................................23
Electrical and Mechanical Specifications!............................................................24
Page of2 24

Setting up your Shaped Dual EnvVCA
1. Power off your Eurorack system.
2. On the back of the Shaped Dual EnvVCA you will see a 10-pin header. The 10-
pin header connects to a Eurorack power header using the included power
cable. Connect the 16-pin end of the power cable to a 16-pin Eurorack power
header on your power supply distribution board and the 10-pin end to the
Shaped Dual EnvVCA with the red stripe on the power cable oriented towards
the bottom of the module.
3. Using the included screws, securely attach the Shaped Dual EnvVCA to the
rails of your case.
4. Power on your Eurorack system.
Note: The Shaped Dual EnvVCA is reverse-polarity protected, but incorrectly
connecting any module in any system can damage other modules on the power bus.
Controls and Jacks
Cycle Buttons
The Cycle buttons toggle the cycling state for each channel. When cycling,
the Shaped Dual EnvVCA behaves like an LFO, with an output waveform
that continuously rises and falls. Each button illuminates orange to indicate
the module is cycling. Note that pressing this button does not reset or alter an
envelope that’s already rising or falling.
Cycling can also be toggled with a gate signal using the Trig jack and switch
(see below).
Rise/Fall Sliders and Switches
The Rise and Fall sliders control the rise and fall times of the envelope.
Moving a slider up makes the rise or fall portion slower, moving it down
makes it faster.
Each slider has a white light that indicates the current stage and output level
of the envelope. When the envelope is in the rise stage, the Rise slider light
will increase in brightness until the envelope hits its maximum. Once the peak
is reached, the Rise light will turn off and the Fall light will turn on, decreasing
in brightness as the envelope falls.
The Rise/Fall switches select the overall range of the sliders. Each slider has
its own switch with three positions: Fast, Med, Slow.
When the switch is flipped to Fast, the envelopes go well into the audio
range, allowing for classic AM, FM, and other fast modulation effects.
The middle position (Med)is designed for typical musical tempos, and can be
useful when using the VCA to make notes at common BPMs.
The Slow position is geared for gradual fades and other slow LFO-style
modulations.
See the Rise and Fall Time Ranges chart on page 6 for more information.
Time CV Jack and Rise/Fall CV Knobs
The Time CV jack modulates the Rise and Fall times of the envelope. The
jack feeds two knobs: Rise CV, and Fall CV. Each of these knobs is an
attenuverter (short for “attenuating inverter”) and controls how much the
control voltage on the Time CV jack will affect the rise or the fall time.
Turning an attenuverter knob to the right of center means that a positive
voltage on the Time CV jack will lengthen the rise/fall time and a negative
voltage will shorten the rise/fall time.
Turning a knob to the left of center gives the opposite effect, meaning that a
positive voltage on the Time CV jack will shorten the the rise/fall time, while a
Page of3 24
Cycle
FallRise
Slow
Fast
Med
Slow
Fast
Time
Fall
Rise

negative voltage will lengthen these durations.
The farther you turn the knob from center in either direction, the more effect
incoming CV will have. When the knob is centered, the signal on the Time
CV jack will have no effect on the rise or fall time.
Next to each knob is a light which indicates the strength and polarity of the
modulation. The light will turn blue when the rise or fall time is being
lengthened by CV, and red when the time is being shortened. The brighter the
light, the more of an effect the CV is having. When the light is off, the Time
CV jack has no effect on the envelope time.
When nothing is plugged into the Time CV jack, the knobs act as fine-tuning
controls for the Rise and Fall times.
Shape Sliders and Lights
The Shape sliders smoothly crossfade between three different envelope
shapes: exponential, linear and logarithmic, as indicated by the graphic
above each slider. Changing the waveshape does not affect the rise or fall
times. The color of the light above the slider indicates the current wave
shape: green for exponential, red for linear, blue for logarithmic. Intermediate
wave shapes are represented by a blend of these colors. The white light on
the slider indicates the amplitude of the envelope, independent of the
envelope Level and Offset settings.
Shape Jack and Shape Knob
Patching a CV signal into the Shape jack will control the waveshape of the
envelope. The Shape knob is an attenuverter and controls how much the
voltage on the Shape jack will change the envelope shape. When the Shape
knob is to the right of center, positive voltage on the jack will cause the shape
to become more logarithmic, while negative voltage will cause the shape to
become more exponential. If the knob is to the left of center, the relationship
is inverse. The farther from center the knob is positioned, the more effect
incoming CV will have. When the knob is centered, CV on the jack will have
no effect. When using the Shape knob or jack in combination with the Shape
slider, the slider acts as a voltage offset. The Shape jack, knob, and slider
can be used together to create waveforms with different shapes for the rise
and fall segments. See Different Waveshapes for Rise and Fall on page 11
for more details.
ENV, Lin 5v, and OR Jacks
The ENV jacks output the waveshaped envelope for each channel. DC offset
and vertical scale are determined by the positions of the Level and Offset
knobs. Envelope shape is determined by the positions of the Shape slider
and knob as well as CV applied to the Shape CV jack. The OR jack
compares each side's ENV output signals and outputs the highest voltage
value between the two at any given moment. The lights indicate the
amplitude and polarity of each envelope. When the envelope is a positive
voltage, its respective light will shine blue. When the envelope is a negative
voltage, the light will shine red. The brightness of each light indicates the
amplitude and offset of the outgoing signal, so when the light is off, this
means the signal is outputting at or around 0V. The Lin 5V jacks output a
linear waveshape from 0V to +5V, independent of Level, Offset, or Shape
settings.
Page of4 24
Lin 5VLin 5V
OR
ENV A ENV B
Shape
Shape

Env. Level and Offset Knobs
The Level knob attenuates and inverts (attenuverts) the envelope output on
each Env Out jack. When Offset is centered, turning Level fully clockwise
will output a positive envelope, with a maximum peak of about 10V. Turning
the knob counter-clockwise inverts the envelope; when fully counter-
clockwise, the output will peak at about -10V.
Turning the Offset knob clockwise will add a positive DC offset between 0V
and 10V to the envelope, while turning the knob counter-clockwise will add a
negative offset between 0V and -10V. See Using Level and Offset on page 23
for more details.
Note that neither the Level nor the Offset knobs affect the envelope going to
the internal VCAs. For example, if the ENV output jack is patched to a
modulation input on an external module while audio is running through the
VCA, Level and Offset can be used to control the amount of modulation
without changing the audio level or Lin 5V envelope signal.
Audio In, Audio Out, and VCA CV Jacks
The Audio In and Out jacks are the input and output of the VCA. The
waveshaped envelope output (pre-Level and Offset knobs) is internally
routed to the VCA CV input. When the envelope is stopped or at 0V, the Out
jack will output silence. As the envelope rises, the signal will get louder until it
becomes as loud as the input signal at the peak of the envelope. As the
envelope falls, the signal will fade back to silence. Audio In Bis normalized
to Audio In A, as indicated by the graphics on the faceplate. So when Audio
In B is unpatched, the Audio In A signal will be sent to both channels.
Patching into Audio In B will break this connection so that both channels are
operating independently. The VCA is normalized to the waveshaped
envelope, so adjusting the Shape slider and CV will affect the VCA.
When patched, the VCA CV jacks break the internal connection between
envelope and VCA, allowing for independent use of the VCA. The VCA CV
input has a range of 0 to 5V, which translates to nearly silent to unity gain.
The VCA has a linear response to the VCA CV, meaning that the voltage on
the VCA CV jack directly sets the attenuation amount (e.g. 2.5V is about 50%
attenuation).
Trig Jacks and Switches (Cycle, AR, ASR)
The Trig input jack and switch can be used with both gates and triggers in
order to generate envelopes. The trigger switch selects the function of the
jack: Cycle, AR or ASR.
When the switch is centered at AR (Attack Release), a trigger will initiate a
single complete envelope if there is no envelope in progress. If the envelope
is rising when a trigger is received, then the trigger is ignored (unless the
RETRIG jumper is installed, see below). If the envelope is falling while a
trigger is received, it will begin rising from its current voltage.
When the switch is flipped down to ASR (Attack Sustain Release), the
envelope will behave similarly to AR mode, but will remain high for as long as
the gate on the Trig jack remains high. Once the gate goes low, the envelope
will switch to its release stage and begin falling. The envelope will always
complete a full rise and fall stage, even if the gate goes low before the rise
stage is done.
When the switch is flipped up to Cycle, a gate toggles the cycle state. If the
Cycle button is off, a gate signal will turn the button on and make the channel
cycle for as long as the gate is held high. If the Cycle button is on, then a
gate signal will turn the button off and cease any cycling for as long as the
gate is held high. See Cycle Button on page 16 for more information.
On the back of the module is a RETRIG jumper for each channel. When this
jumper is installed, the envelope will immediately jump to 0V and start rising
any time a trigger is received (regardless of the switch position). This can
cause a click on the VCA output, so the jumper is not installed at the factory.
Page of5 24
Level
Offset
VCA CV
In
Audio B
Out
A
Cycle
AR
ASR
Trig

Follow Jack
The Follow jack is the input of a slew limiter, and can also be used for
complex envelope generation, exotic audio filtering, envelope following and
sidechaining.
Whenever the internal envelope is not triggered or cycling, the envelope
output will rise or fall in order to match the voltage level present on the
Follow jack. However, the rate of rise and fall times is limited by the positions
of the Rise/Fall sliders and the CV amounts. That is, the envelope output will
try to “follow” the signal present on the Follow jack, but it can only rise and
fall as fast as the envelope would rise/fall if it were to be triggered. Since
“slew” is the rate of change, we call this “slew limiting”.
The Follow jack can be used for envelope following, sidechaining,
waveshaping, audio filtering, portamento and more. See Fundamentals of the
Follow Jack on page 17 for more information.
EOR and EOF Output Jacks
The EOR (End of Rise) jack is specific to Channel A. It outputs a gate that
goes high when the rise stage ends and the fall stage begins. It remains high
as long as the envelope is falling, and goes low when the envelope
completes. When the envelope is not running, the EOR jack will stay low. The
EOR light will shine orange whenever the output is high.
The EOF (End of Fall) jack is specific to Channel B. It outputs a gate that
goes high when the fall stage ends, and remains high until the envelope
begins rising. Said another way, the gate at the EOF jack only goes low
during the rise stage. The EOF light will shine orange when the EOF output is
high.
Rise and Fall Time Ranges
Note that the switch positions have little effect on the range obtained by using CV. This is intentional, to
allow external modules control over the full range.
Because of its analog nature, the maximum and minimum rise and fall times vary from unit to unit. The
table above shows typical values.
The rise and fall times will not necessarily be equal when the sliders are in the same position. For
precisely equal rise and fall times, manual adjustment is usually needed.
Page of6 24
Follow
Switch Position
Slider
Range
(total env.
time)
Max Range
with CV
(total env.
time)
Use Cases
Slow
2 min. to
~2Hz
~30-60 min.
to 2.5kHz
Gradual, slow fades or modulation changes
occurring over the course of a long time.
Med
~10 sec. to
~30Hz
Generally suited for typical musical tempos. Useful
for making notes, from snappy percussive sounds to
long decays. The slower slider settings approach
LFO ranges.
Fast
~2Hz to
~500Hz
Good for using as an audio oscillator, or for FM, AM
or other audio-rate modulation. Snappy attacks and
sharp decays.
Fast
Med
Slow
Fast
Med
Slow
Fast
Med
Slow
EOR
EOF

Patch: Making Notes
Making Notes (Basic)
Patch a sound source into the Audio In A jack, and patch the Audio Out A jack to your mixer or amp
so you can hear it on speakers or headphones. When choosing the sound source, try to find something
that makes a continuous tone or drone, such as a VCO like the Ensemble Oscillator.
When the left Cycle button is on (button is shining orange), you should hear notes being played at a
steady tempo. The notes should have a sharp attack (quick fade-in) and longer decay (slower fade-
out).
Try moving the Rise slider up and listen to how the sound fades in more slowly. Then move the Fall
slider down and hear how the fade-out gets faster. Continue to experiment with the slider positions,
listening to how the sound and tempo change. Try flipping the switches to Fast and hear how much
faster the envelope gets.
Adjusting the Shape slider to exponential will cause the rise and fall to sound more snappy while
setting the slider to logarithmic will cause the envelope to sound more like a gate, with very quick rises
and falls. Notice how adjusting the Shape slider does not affect the cycle tempo.
Next, patch the ENV output jack to a modulation input on the sound source. For example, if you’re
using the Ensemble Oscillator, try patching it to the Warp jack. For other VCOs, try a PWM or wave-
shaper input. Adjust the Level and Offset knobs to control the amount of modulation. When both knobs
are centered, you should hear no modulation.
Tip: If you want to use the Shape slider to control the waveshape of the modulation without changing
the VCA, patch Lin 5V to VCA CV in order to bypass the internal connection between the shaped
envelope and the VCA.
Making Notes in Stereo
So far we’ve just used Channel A, but this patch can be duplicated on Channel B to process two sound
sources or a single stereo sound source.Try doing this now, by patching the second output of the
Ensemble Oscillator or some other sound source into the Audio In B jack. If you don’t have another
Page of7 24
Cycle
AR
ASR
Cycle
AR
ASR
Rise Fall
Shaped Dual EnvVCA
TimeTime
Follow
VCA CVVCA CV
In
Audio BAudio A
Out
In
Out Lin 5VLin 5V
OR
Shape
Rise Fall
Slow
Fast
Med
Slow
Fast
Trig Cycle
Offset
Level
EOF
Fall
Rise
Shape Shape
Follow
ENV A ENV B
Shape
FallRise
Slow
Fast
Med
Slow
Fast
Trig
Cycle
Offset
Level
EOR A
To mixer/output
amp
From sound source
(e.g. a VCO)
Cycle on
Switches set to
Med
Rise slider at Fast,
Fall slider in
middle (adjust to
taste)
Optional:
To VCO
modulation input
(FM, waveshape,
etc.)
Optional:
adjust amount of
modulation
Stereo patch: to
mixer/output amp
Stereo: From right
channel of sound
source (or a
different sound
source)
Optional:
Adjust
waveshapes

sound source, you could leave Audio In B unpatched and the signal from In A will be routed there
automatically, but using a stereo sound source (or two mono sound sources) has a nicer effect.
Patch the Audio Out B jack to the mixer (adjust the panning if your mixer supports that). Turn Channel
B Cycle on. Adjust the Rise and Fall sliders and set the switches to center. You should hear both
sound sources playing at different tempos.
Synchronizing Channels: Making Notes Using Triggers
With the previous patch, the tempo of each channel is linked to the rise and fall times of the envelopes.
It’s not possible, for example, to have quick, short notes at a slow tempo. It’s also nearly impossible to
adjust the sliders so both channels are going at the exact same tempo.
By turning Channel A’s Cycle off and patching the EOF trigger from Channel B to Channel A’s Trig jack,
we can synchronize the channels and separate Channel A’s envelope length from its tempo. Try doing
this now. Flip Channel A’s Trig switch to AR.
Every time Channel B ends an envelope and begins a new one, an EOF pulse fires, causing Channel A
to start an envelope. Channel A’s Rise/Fall sliders control the envelope length without changing the
tempo. Channel B’s sliders control the tempo for both channels as well as the envelope for Channel B.
Creating Stereo Motion
Since the channels are now synchronized, we can create motion in the stereo field. The effect is best if
you use your mixer to pan the two Audio Outs to the left and right. You might also want to unpatch the
Audio In B jack so that the same mono signal is used on both channels. Now play with the Rise/Fall
and Shape sliders. Try increasing Channel A’s Rise time by setting the slider just a little bit higher than
Channel B. This gives Channel A a slight delay since it will take longer to rise than Channel B. The
delay will be perceived as a right-to-left motion (assuming Channel A is in the left ear, and Channel B is
in the right ear). Adjusting the Shape slider for either channel will also allow for some different stereo
qualities. The key in this patch is to keep the channel envelopes similar, but different enough to create
the illusion of motion.
Page of8 24
Cycle
AR
ASR
Cycle
AR
ASR
Rise Fall
Shaped Dual EnvVCA
TimeTime
Follow
VCA CVVCA CV
In
Audio BAudio A
Out
In
Out Lin 5VLin 5V
OR
Shape
Rise Fall
Slow
Fast
Med
Slow
Fast
Trig Cycle
Offset
Level
EOF
Fall
Rise
Shape Shape
Follow
ENV A ENV B
Shape
FallRise
Slow
Fast
Med
Slow
Fast
Trig
Cycle
Offset
Level
EOR A
To mixer/output
amp
From left channel
of sound source
Cycle off
Switches set to
Med
Channel A Rise/
Fall sliders set
channel A note
length
To VCO
modulation input
(FM,
waveshape…)
Optional:
adjust amount of
modulation
To mixer/output
amp
From right channel
of sound source
Cycle on
Channel B Rise/
Fall sliders set
overall tempo, and
channel B note
length
Patch EOF to
Channel A Trigger
Optional:
adjust amount of
modulation
Trig switch to
AR

Using a Keyboard or Sequencer
Instead of using Channel B to set the tempo, you could use an external CV/Gate keyboard or
sequencer. Turn off Cycle and patch the gate output of the keyboard or sequencer into Channel B’s
Trig jack. Whenever you fire a gate by pressing a key, Channel B will fire an envelope, and also trigger
Channel A. The tempo at which you play the keyboard or sequencer now determines the tempo of each
channel’s notes.
Keeping Channel A’s Trig switch at AR, try Channel B’s Trig switch in all three positions as you play
notes on the keyboard or sequencer. Play with the duration of key-presses (or pulse width of sequencer
step outputs), and see the effect this has on the sound in each Trig position. When Trig is set to Cycle,
engage and dis-engage the Cycle button and note the effect this has when holding a key down.
If you’re using a VCO as a sound source and you also want to control the pitch of the notes with the
keyboard, patch the keyboard CV output to the pitch CV (1V/oct) input on the VCO.
Notice that when you fire a gate, Channel B will play first, and then Channel A. If you want them both to
start at the same time, you could unpatch the cable from EOF to Channel A’s Trig jack, and instead use
a splitter or mult to patch the keyboard’s gate output into both Channel’s Trig jack.
Adding Chaos
You can create some inter-related pattens by patching Channel A’s EOR jack into Channel B’s Trigger
jack. Re-patch EOF to Channel A’s Trigger jack if you had removed it to use a keyboard. Turn off both
Cycle buttons. Now both channels trigger each other. For some extra chaos, patch the OR jack to one
of the Time CV jacks. Press one of the Cycle buttons to start the chain of events, and play with the
sliders, the Rise/Fall CV knobs, and the Level and Offset knobs until you find sweet spots where
random patterns emerge. You can also try adjusting the shape of either channel or flipping the Trig
switch to different settings for more randomness.
Page of9 24

Patch: Waveshaping
Modulating Waveshape
A unique feature of the Shaped Dual EnvVCA is its ability to modulate the envelope waveshape
without changing the timing. To demonstrate this, we’ll create a simple patch that makes notes with
Channel A and uses Channel B to modulate the waveshape of Channel A. Patch a sound source, such
as the Ensemble Oscillator, into Audio In A. Patch Audio Out A to your mixer. Set Channel A’s Rise/
Fall sliders to taste. You should be hearing notes. If you have an oscilloscope, view the waveform on
ENV A (adjust Level and Offset as needed). Move Channel A’s Shape slider all the way to the left and
listen to the exponential waveshape. Slowly move the slider to the right and listen how the sound
changes. When you’re done experimenting, set the slider all the way to the left.
Set Channel B’s switches to Slow and Rise/Fall sliders to center. Turn on Channel B’s Cycle button.
Make sure Channel B is going at least 10 times as slow as Channel A. Now patch Channel B’s Lin 5V
jack to Channel A’s Shape jack. Turn Channel A’s Shape attenuator knob all the way up. You should
now be hearing the waveshape slowly change from exponential, to linear, to logarithmic, and back.
Optionally, you can patch one of the Env outputs to modulate Twist or Warp on the Ensemble
Oscillator. Using the OR output jack is particularly interesting in this case since different channels will
be responsible for the modulation at different times. If you want to use a stereo signal, you can patch
Channel A’s ENV A jack to Channel B’s VCA CV jack and adjust Channel A’s Level and Offset knobs
until the two channels sound balanced.
Page of10 24
Sliders in middle
(adjust to taste)
Shape knob
fully CW
Shape slider set left
Cycle
AR
ASR
Cycle
AR
ASR
Rise Fall
Shaped Dual EnvVCA
TimeTime
Follow
VCA CVVCA CV
In
Audio BAudio A
Out
In
Out Lin 5VLin 5V
OR
Shape
Rise Fall
Slow
Fast
Med
Slow
Fast
Trig Cycle
Offset
Level
EOF
Fall
Rise
Shape Shape
Follow
ENV A ENV B
Shape
FallRise
Slow
Fast
Med
Slow
Fast
Trig
Cycle
Offset
Level
EOR A
To mixer/output
amp
From sound source
(e.g. a VCO)
Cycles on
Channel A
switches to Med
Rise/Fall near the
center (adjust to
taste)
Channel B
switches to
Slow

Different Waveshapes for Rise and Fall
Log Rise With Expo Fall
In this patch we’ll take advantage of the EOR jack to create separate waveshapes during the rise and
fall portions of an envelope. It’s common to use logarithmic rises with exponential falls in order to create
snappy envelopes.
On Channel A, patch the EOR jack to the Shape CV Jack. Turn the Shape CV knob fully counter-
clockwise and set the Shape slider all the way to the right. Patch ENV A to a modulation input on
another module. You also could patch a sound source into Audio In A and patch Audio Out A to a
mixer.
During the rise phase, the EOR jack is low, so there is no Shape CV. The shape is set by the slider
position, which is logarithmic. During the fall phase, the EOR jack sends a high voltage into the Shape
CV jack. The Shape CV knob inverts this voltage, causing the shape to be exponential.
Any Combination of Shapes
Any combination of waveshapes can be set for rise and fall by first using Channel A’s Shape slider to
set the rise shape, and then using Channel A’s Shape knob to set the fall shape. For instance, to create
an exponential rise and logarithmic fall, simply reverse the settings by turning the Shape CV knob fully
clockwise and moving the slider all the way left.
Channel B can also generate different waveshapes on the rise and fall by patching the EOF jack into
Channel B’s Shape CV jack. In this case, Channel B’s Shape slider sets the fall shape, and Channel
B’s Shape knob sets the rise shape.
See the Table of Envelope Shapes on page 22 for an illustration of various waveshapes.
Page of11 24
Cycle
AR
ASR
Cycle
AR
ASR
Rise Fall
Shaped Dual EnvVCA
TimeTime
Follow
VCA CVVCA CV
In
Audio BAudio A
Out
In
Out Lin 5VLin 5V
OR
Shape
Rise Fall
Slow
Fast
Med
Slow
Fast
Trig Cycle
Offset
Level
EOF
Fall
Rise
Shape Shape
Follow
ENV A ENV B
Shape
FallRise
Slow
Fast
Med
Slow
Fast
Trig
Cycle
Offset
Level
EOR A
Shape slider sets
rise shape
Shape knob sets
fall shape (adjust
after setting
Shape slider)
To modulation
input on another
module (or
oscilloscope)

Patch: Modulating Time
Rapid Bursts
In this patch we’ll make a rapid burst effect where the notes play at a steady tempo for a while, and
then periodically play in a rapid burst. Start with Cycle on and the Audio In/Out jacks patched to a
sound source and mixer. Set the Rise and Fall switches to Med, and set the sliders to taste. You
should be hearing notes at a steady tempo. If you like, patch ENV A output to a modulation input on the
sound source and adjust Level to set the amount of modulation.
Turn on Cycle for Channel B and adjust the Rise/Fall sliders and switches so that it’s cycling at least
four times as slowly as Channel A. Patch the EOF output of Channel B to the Time CV input of
Channel A. Turn Channel A’s Rise CV and Fall CV attenuverters slightly to the left, so that when the the
EOF jack fires a pulse, the notes play at a faster rate.
Adjusting the Rise time of Channel B will change the pulse width of the EOF pulse, thus controlling the
duration of the rapid bursts. The sum of the Rise and Fall times on Channel B controls how often the
rapid bursts occur. Channel A's Rise and Fall CV knobs control how rapid the bursts are. Try adjusting
these parameters slightly to hear the effect.
Ratcheting
The previous patch alternates between two speeds (normal and rapid). A ratcheting effect is when the
speed gradually increases. To create this effect, unpatch the cable from EOF to Time CV, and instead
patch Time CV to ENV B. Turn off Channel B’s Cycle button and patch a slow trigger source (LFO,
clock divider) to Channel B’s Trig jack. Set Channel B’s Trig switch to AR. Start with Channel B’s Rise
slider in the middle, Fall slider at Fast, and switches set to Med. Adjust Channel B’s Level knob to set
how much the speed increases.
Page of12 24
Cycle
AR
ASR
Cycle
AR
ASR
Rise Fall
Shaped Dual EnvVCA
TimeTime
Follow
VCA CVVCA CV
In
Audio BAudio A
Out
In
Out Lin 5VLin 5V
OR
Shape
Rise Fall
Slow
Fast
Med
Slow
Fast
Trig Cycle
Offset
Level
EOF
Fall
Rise
Shape Shape
Follow
ENV A ENV B
Shape
FallRise
Slow
Fast
Med
Slow
Fast
Trig
Cycle
Offset
Level
EOR A
To mixer/output
amp
From sound source
(e.g. a VCO)
Cycle on
Switches set
to Med.
Sliders set to
taste
Rise/Fall CV
turned to the
left. Controls
speed of
ratcheted
envelopes.
Cycle on
Switches set to
Slow. Sliders set
to taste. Rise
time sets how
long ratcheting
lasts. Rise plus
Fall sets how
often ratcheting
occurs.
Optional: To VCO
modulation input

Patch: Making an Oscillator and Synth Drums"
Making an Oscillator
In this patch we’ll use Channel A of the Shaped Dual EnvVCA as an oscillator. Flip the Rise and Fall
switches of Channel A to Fast. Patch the ENV A output jack to a mixer. Engage the Cycle button to
begin oscillation. Channel A’s Level sets the volume. You can change the pitch by adjusting the Rise/
Fall sliders. If both sliders are approximately at the same position and Shape is in the center, you’ll get
a triangle wave output. If one slider is substantially higher or lower than the other, the output will
resemble a ramp or saw wave. For pulse wave shapes, you can take the signal from the EOR jack
instead of ENV A, and then adjusting the sliders separately will change the pulse width. Adjusting the
Shape slider on Channel A will change the timbre.
Making a Kick Drum
To make a kick drum sound, first use the sliders to set the pitch of Channel A low enough so that you
can’t hear sound. If there’s some clicking, that’s OK. Now we will modulate the pitch by patching ENV B
to Channel A’s Time CV jack. Set Channel A’s Rise and Fall CV attenuverters to be fully CCW. Turn on
Channel B’s Cycle button or fire triggers into Channel B’s Trigger jack to hear the pitch of Channel A
modulate. Adjusting the Level knob on Channel B will change the amount the pitch rises; typically for a
classic analog kick sound, the knob should be around 1 or 2 o’clock. The Rise and Fall sliders of
Channel B will adjust the attack and decay. A typical drum will have a sharp attack and slower decay, so
start with the Rise slider and switch at Fast, and the Fall slider and switch in the middle positions. The
base pitch of the drum can be fine-tuned with Channel B’s Offset knob.
An exponential modulation curve makes a more extreme kick drum sound. Try adjusting Channel B’s
Shape slider to the left and notice how the drum has more “punch”.
Page of13 24
Cycle
AR
ASR
Cycle
AR
ASR
Rise Fall
Shaped Dual EnvVCA
TimeTime
Follow
VCA CVVCA CV
In
Audio BAudio A
Out
In
Out Lin 5VLin 5V
OR
Shape
Rise Fall
Slow
Fast
Med
Slow
Fast
Trig Cycle
Offset
Level
EOF
Fall
Rise
Shape Shape
Follow
ENV A ENV B
Shape
FallRise
Slow
Fast
Med
Slow
Fast
Trig
Cycle
Offset
Level
EOR A
Cycle on if not using
external trigger
To mixer/output
amp
Cycle on
Both switches
set to Fast.
Rise and Fall sliders
control attack and
decay of kick drum
Rise and Fall
Sliders set the
base pitch and
timbre
Rise/Fall CV
fully to the left
Rise switch to Fast.
Fall switch to Med.
Level controls
amount of
modulation
Level controls
volume
From external trigger
source (gate
sequencer, clock, …)
Shape changes
timbre
Optional: Move
Shape slider towards
expo for more punch
Offset at center.

Making Other Synth Drum Sounds
In the Making an Oscillator patch, we created a kick drum which decays to an inaudible frequency
below the range of human hearing. To create a higher-pitched drum, such as a tom-tom, we will need a
VCA to cut off the audio after the drum decays. Using a VCA also gets rid of the clicking between drum
hits which happens when not using a triangle wave.
Raise the pitch of Channel A using the sliders or Channel B’s Offset knob. You should hear a steady
tone between Channel B firing (this is especially noticeable if you’re using external triggers). Now we’ll
route this sound through Channel B’s VCA. Unpatch the cable going to the mixer and patch it into
Audio Out B instead. Patch a cable from ENV A to Audio In B. Now you should hear a similar synth
drum sound, but it will be silent between hits.
Try setting Channel B’s Shape slider to various positions left of center and listen how the “punch” of the
drum changes. As you do this, you may need to adjust Channel B’s Offset knob to keep the pitch in the
desired range. You may also want to patch Channel B’s Lin 5V to its VCA CV so that the VCA’s
response doesn’t change as you adjust the Shape slider.
To get more complex waveshapes, patch EOR to Channel A’s Shape CV jack and adjust the Shape
knob (see Different Waveshapes for Rise and Fall patch on page 11)
To add some noise to the drum sound, you can patch an external oscillator into Audio In A. Then move
the patch cable going from ENV A to Audio In B so that it goes from Audio Out A to Audio In B. The
external oscillator will be amplitude modulated (AM) with the synth drum sound, and this resulting
sound will be VCA’ed with Channel B’s envelope. Play with Channel A’s sliders and Rise/Fall CV knobs
to hear the range of possible sounds. Next, use the OR output jack to modulate the external oscillator in
time with the synth sound.
Try adding slight modulation to the Time CV or Shape CV of Channel B to create organic, naturally
changing drum sounds. A slow LFO or a CV sequencer will work nicely.
Page of14 24
Cycle
AR
ASR
Cycle
AR
ASR
Rise Fall
Shaped Dual EnvVCA
TimeTime
Follow
VCA CVVCA CV
In
Audio BAudio A
Out
In
Out Lin 5VLin 5V
OR
Shape
Rise Fall
Slow
Fast
Med
Slow
Fast
Trig Cycle
Offset
Level
EOF
Fall
Rise
Shape Shape
Follow
ENV A ENV B
Shape
FallRise
Slow
Fast
Med
Slow
Fast
Trig
Cycle
Offset
Level
EOR A
Cycle on if not using
external trigger
To mixer/output amp
Cycle on
Both switches
set to Fast.
Rise and Fall
sliders control
attack and decay of
kick drum
Rise and Fall
Sliders set the
base pitch and
timbre
Rise/Fall CV
fully to the left
Rise switch to Fast.
Fall switch to Med.
Level controls
amount of
modulation
Level controls
volume
From external trigger
source (gate
sequencer, clock, …)
Shape slider
and knob
change timbre
Optional: Move
Shape slider towards
expo for more punch
Offset at center.
Optional: to
Audio In B
Optional:
Sound source
to be AM’ed

Self-patching ideas
Frequency Modulation (FM)
Turn both Cycle buttons on, and set all switches to Fast. Start with all sliders in the center position.
Use Channel B to modulate the frequency of Channel A by patching ENV B into Channel A’s Time CV
jack. Adjust both Rise and Fall CV knobs to around 9:00. Turn both Level knobs fully clockwise and
center Offset knobs. Listen to the output on ENV A, or for a mix of both oscillators, use OR jack. Slowly
adjust Channel B’s sliders and listen to how the sound changes. Then slowly adjust Channel A’s sliders
and Rise/Fall CV knobs to hear the effect.
The Rise and Fall sliders of Channel B control the modulation frequency, and Channel A’s Rise/Fall CV
knobs control the modulation amount. Channel A’s sliders control the base frequency, also known as
the carrier frequency.
Chaotic FM
For chaos, start with the FM patch above, and then use Channel A to modulate Channel B by patching
ENV A into Channel B’s Time CV. Start with Channel B’s Rise and Fall CV knobs set to about 10:00.
Take the output from the OR jack. To find interesting chaotic sounds, you probably will need to move
the sliders to a slower position and the Rise/Fall CV knobs more towards center than in the FM patch.
Utility Patches
Attenuator
Patch a signal that you want to attenuate into Audio In (either channel), and take the output from
Audio Out. Patch the channel's ENV output to VCA CV. Use Offset to adjust the attenuation amount.
Keep in mind that the VCA only responds to positive CV, so if Offset is anywhere left of center, the
output will be silent. If you are using the envelope portion of the channel (Cycle is on or you are
triggering the channel), set Level to center or else the envelope will bleed into the attenuator output.
Trigger Delay With Pulse Width Control
Turn Channel A’s Cycle off. Send a trigger into Channel A’s Trig jack and flip the Trig switch to AR.
Take the output from EOR. Adjust the Rise slider and switch to set the trigger delay time (rising edge of
incoming trigger to rising edge of outgoing trigger). Set the Fall slider and switch to control the width of
the outgoing trigger. If you flip the Trig switch to ASR, the trigger output will be delayed from the falling
edge of the incoming trigger, and rise times shorter than the incoming trigger’s pulse width will not have
an effect.
Inverted Trigger Delay (With Pulse Width Control)
Same as the previous patch, but use Channel B’s Trig jack and EOF. Rise controls the amount of
delay (rising edge of incoming trigger to falling edge of outgoing inverted trigger)and Fall controls the
width of the inverted trigger.
DC generator (Manual CV)
When a channel is not running, the Offset knob will produce a steady DC voltage on the ENV output
jack. If the channel is running, set Level to center or else the envelope will bleed into the output.
Ducking (Sidechaining)
A ducking effect reduces the volume of a sound at the same time a secondary sound plays. If the
secondary sound is generated by triggers in your patch, you can easily create this on the Shaped Dual
EnvVCA by generating an inverted envelope and patching it into the VCA.
To achieve this effect, split the trigger that’s triggering the secondary sound and patch it into the Trig
jack of one channel. Turn Cycle off. Adjust Rise and Fall to create the envelope you want (typically the
rise will be shorter than the fall). Patch an audio signal into Audio In and take the output from Audio
Out. You should hear your sound play every time the trigger fires. In order to create the inverse
behavior (get more quiet when the trigger fires), patch the ENV output to VCA CV,turn Level to about
9:00 and Offset to about 3:00.
If the secondary sound source is not generated by triggers in your patch (perhaps because it’s an audio
track), you can, see Sidechaining (Envelope Following) on page 18.
Page of15 24

Creating Envelopes with Trig Jack and Switch, Cycle Button, and Follow Jack
There are several ways to generate an envelope with the Shaped
Dual EnvVCA: using the Trig jack and switch, pressing the Cycle
button or using the Follow jack.
Triggering With Switch Set To AR
When the switch is set to AR, the Trig jack starts an envelope when it
receives a trigger or gate. It only responds to rising edges. Figure 1
shows how a long or short pulse will cause identical envelopes since
the pulse width and falling edge of the signal are ignored.
Triggering With Switch Set to ASR
An ASR (attack-sustain-release) envelope is trapezoidal, with a rising
slope (attack), a flat plateau (sustain), and a falling slope (release).
See Figure 2. The width of the sustain stage is controlled by the width
of the gate input, the longer a gate is held high, the longer the sustain
stage. If the gate input goes low before the rise stage completes, there
will be no sustain, as the first pulse in Figure 2 illustrates.
Triggering With RETRIG Jumper Off (Factory Default)
If the envelope is already rising when a trigger is received, then the
trigger is ignored (unless the RETRIG jumper is installed). If the
envelope is falling when a trigger is received, it will begin rising from its
current voltage. Figure 3 demonstrates this: the fifth and seventh
triggers occur while the envelope is falling and cause it to begin rising
mid-fall. The rest of the triggers either occur while the envelope is
rising and are ignored, or while the envelope is not running, causing it
to start.
Triggering With RETRIG Jumper On
Figure 4 shows how the RETRIG jumper changes the behavior. With
the jumper installed, a trigger will always reset the envelope to zero
and begin rising, regardless the stage of the envelope. This sharp
transition to 0V can cause a click when used with audio, so the jumper
is not installed by default.
Cycle Button and Triggering With Switch Set To Cycle
The Cycle button is a simple way to initiate an envelope. When the
button is on, envelopes will cycle continuously. The button is latching,
so pressing it once will make the module output envelopes until you
press the button again. Once an envelope begins, pressing the Cycle
button again will not immediately stop the envelope. Instead, the
envelope will stop after finishing its fall stage.
When the Trig switch is set to Cycle, a high gate on the Trig jack
toggles the cycling state. This works in tandem with the Cycle button.
If a channel’s button is initially off, a gate signal at the Trig jack will
toggle it on. If the button is initially on, a gate at the jack will toggle it
off. The Cycle button will shine orange whenever the combination of
Trig jack and Cycle button causes the envelopes to cycle. Note that
envelopes generated when the Trig switch is set to Cycle do not have
a sustain portion.
In Figure 5,the Cycle button is initially off, and the incoming gate
signal on the Trig jack causes the envelope to cycle for as long as the
gate is high. In this case, as the pulse width of the gate signal gets
wider, the channel outputs more cycles.
Page of16 24
Figure 1: AR – Trigger width does
not change Env output.
Figure 3: RETRIG jumper off.
Triggers on rise stage have no
effect. Triggers on fall stage switch
to rising.
Figure 4: RETRIG jumper installed.
Triggers always restart the envelope.
Figure 2: ASR – Trigger width
controls sustain length

Figure 6 shows the opposite state; the Cycle button is initially on, so the incoming gate signal stops
cycling for as long as the gate is high. In this case, as the pulse width of the gate signal gets wider,
there are longer pauses between groups of envelopes.
Note that the first pulse in Figure 6 does not stop the envelopes, and the three rapid pulses in Figure 5
only cause one envelope. This illustrates an important aspect of the Shaped Dual EnvVCA: the state
of the Cycle button and Trig jack when the switch is set to Cycle only matter when the envelope is
stopped (at 0V). Any combination of gates and button presses while the envelope is running have no
effect; it’s only when the envelope finishes running that the Cycle jack or button can make it cycle
again.
Follow Jack With Gates
Figure 7 illustrates the use of gates on the Follow
jack. A gate signal will cause the envelope to rise as
long as the gate is high. When the gate goes low,
the envelope will fall.
The fourth gate in Figure 7 shows that if the gate is
held high while the envelope reaches its maximum,
the envelope will hold (sustain) until the gate is
released. This is an alternative way to create an
ASR envelope (Attack Sustain Release)
independent of the Trig switch position.
The short burst of pulses at the end illustrates how
the Follow jack can be utilized to create complex
envelope shapes using only a sequence of gates.
The Follow jack can be used with more than gates, see the next section for a detailed discussion.
!
Fundamentals of the Follow Jack
The Follow jack causes an envelope to rise or fall in order to “follow” the signal on the jack. Sending a
high voltage (5V) into the Follow jack will cause the envelope to rise. Sending a low voltage (0V) will
cause it to fall. This can be seen in Figure 7 of the previous section.
Sending voltages up to 5V, such as a waveform from an LFO or an audio signal, will have more
complex effects.
There are two basic rules that govern this jack:
Rule 1: If the voltage on the Follow jack is greater than the envelope voltage, the envelope will
rise; if the voltage on the Follow jack is less than the envelope voltage, the envelope will fall.
That is, the envelope will always “seek” the Follow signal: it will go up if the Follow signal is higher,
and it will go down if the Follow signal is lower. This is where the term “follow” originates.
Rule 2: The envelope can only rise and fall at the speed set by the Rise/Fall controls and CV.
Page of17 24
Figure 5: When Cycle button is off, high gate on Trig jack
makes envelope run (switch set to Cycle).
Figure 6: When Cycle button is on, high gate on Trig jack
makes envelope stop (switch set to Cycle).
Figure 7: Sending gates into the Follow jack. When the
input gate goes high, the envelope rises; when the input
goes low, the envelope falls.

This means that if the Follow jack suddenly jumps up (for example, when a gate is applied), the
envelope will try to follow that jump by rising, but it can only rise as fast as the controls allow it. The rate
of change, or slew, is limited, thus we call the Follow circuit a “slew limiter”.
Note that the term “envelope voltage” in Rule 1 refers to the internal envelope voltage, which is the
signal on the Lin 5V jack. The is the envelope before the Shape controls, Level and Offset knobs, and
ENV jack output driver. This envelope has a maximum of 5V and minimum of 0V, which is why the
Follow jack only responds to voltages from 0V to 5V. The ENV jack’s output driver doubles the internal
voltage, so a 5V internal envelope corresponds to approximately 10V envelope on the ENV output jack
when Level is set to maximum and Offset is centered.
Armed with these two basic rules, we can now showcase some advanced uses for the Follow jack in
the following sections.
Audio Filter
The Follow jack can be used as an exotic audio low-pass filter by taking advantage of its slew-limiting
properties. First, the audio signal must be shifted up such that it’s within the range of 0V to 5V. Typically
a level shifter can be used to add the required DC offset. You may also need to attenuate the audio so
that it’s no more than 5V. Any signal outside this range will be clipped, resulting in harsh distortion.
Patch this adjusted audio into the Follow jack. Patch the ENV output jack to your mixer/amp. Turn
Level all the way up and turn Offset to center. To start, set the Rise/Fall sliders and switches to the
fastest positions. Send a steady positive voltage into the Time CV jack and turn the Rise/Fall CV knobs
all the way down.
At this point you should be hearing an audio signal that is similar to the original signal.
Now make the rise and fall times slower by adjusting the Rise/Fall CV knobs and sliders, or by
adjusting the CV patched into the Time CV jack. As you do this, you should hear the audio get more
muffled, as the slew becomes limited and higher frequencies can no longer pass.
To make more exotic sounds, try only adjusting the rise or the fall time. This will let the rising portions
and falling portions of higher frequencies pass differently, creating some unique harmonics.
Waveshaper
By limiting the slew, wave shapes with sharper transitions can be altered to have smoother transitions.
For instance, feeding a square wave into the Follow jack will produce a trapezoidal or triangular wave
on the ENV output jack. Adjust the Rise/Fall sliders and switches to get a maximum amplitude output
waveform while still performing the desired amount of waveshaping. These controls will need to be re-
adjusted if the frequency of the waveform changes. You may be able to use the Time CV jack and
Rise/Fall CV knobs to track the frequency and create a somewhat consistent variable-frequency wave
shaper. You can also change the curve of a wave using the Shape slider.
Portamento/Glide
The output of a CV/Gate keyboard or a sequencer is often a step-wave, meaning that the voltage jumps
(or “steps”) from one voltage to the next as the notes are played. When this is patched into a VCO, the
result is a sequence of notes that jump from one pitch to the next. Adding in some slew causes the
notes to “glide” from one pitch to the next. This effect is known as portamento or glissando. The
Shaped Dual EnvVCA can perform this effect by patching the step-wave into the Follow jack and
taking the output from the ENV output jack. The amount of glide effect is controlled by the rise and fall
times. If you’re patched into the pitch input of a VCO, you can adjust the tuning with the Level and
Offset knobs. Keep in mind that the Shaped Dual EnvVCA is not designed to be a precision
portamento effect, so tuning will not be accurate over a wide range.
Sidechaining (Envelope Following)
The Follow jack can be used to create an envelope that follows an audio signal’s envelope. This
envelope can be inverted and used to control a VCA, creating a “ducking” effect on another sound. This
technique is called sidechaining.
A common application is to use a kick drum to duck another sound source, for example, a background
drone. Patch an audio source that’s making a kick drum sound into the Follow jack of Channel B. Make
sure Cycle is off. Start with the switches at Med, the Rise slider all the way down, and the Fall slider in
the center. If you turn Level up, the ENV B jack will be outputting an envelope that roughly follows the
kick drum’s envelope. Adjusting Rise and Fall will control the attack and release of the envelope, that
is, how quickly the envelope responds to the attack and release of the kick drum.
Page of18 24

For this example we want to invert the envelope, so turn Level all the way counter-clockwise, and turn
Offset to around 2:00. ENV B will now be outputting an inverted envelope that rests at about 5V and
then ducks down when the kick drum plays. Patch this inverted envelope into Channel A’s VCA CV
jack. Run the audio that you want to be ducked (e.g. a drone sound) into Channel A’s Audio In, and
listen to the output on Audio Out. You should hear the drone play at normal volume, and then briefly
get more quiet whenever the kick drum fires. Try listening to the drone and the kick drum
simultaneously to get the full effect.
Adjust Channel B’s Rise and Fall sliders to control how quickly the envelope responds. If the sliders
are set too fast, the envelope will trace the individual peaks of the sound wave, not the overall
envelope, and the result will be like a subtle AM effect. If the sliders are set too slow, the volume won’t
change much when the kick drum fires.
You can also adjust Channel B’s Offset and Level knobs to control the dynamic range of the ducking. If
you want less ducking, turn Level towards center to reduce the amplitude of the envelope. On the other
hand, if the kick drum is quiet you may need to turn Level towards the extreme counter-clockwise
position to generate an envelope with enough amplitude to get the amount of ducking you want. Offset
almost always needs to be between 1:00 and 3:00. If it’s too low, the output will be too quiet, and if it’s
too high, the output will be at maximum volume with very little ducking.
Using Non-Linear Shapes With Follow
When you feed a signal into the Follow jack, the ENV output jack produces different waveforms
depending on the Shape settings. Figure 8 illustrates variation between the outputs with the Shape
slider in different positions. The blue trace is an audio recording of three drum hits, which is fed into the
Follow jack. The magenta trace shows the output when Shape is set to linear: the peaks of this output
are roughly proportional to the peak levels of the input signal.
Since exponential curves change a small amount to small signals, and a large amount to large signals,
when Shape is exponential, low voltages (near 0V) will be diminished, and higher voltages (near 5V)
will be amplified. This can be seen by the orange curve in Figure 8: only the loudest peaks of the blue
trace cause any noticeable output.
On the other hand, logarithmic curves change a
large amount to small signals, and a small amount
to large signals. Setting Shape to this curve
produces the green trace: tiny signals cause
relatively large peaks in the output, while large
differences in the input peaks cause little differences
in the output peaks.
These differences between Shape settings when
using the Follow jack can be used to select the
types of signals you want a channel to respond to.
For example, if you want to only output an envelope
when a loud kick drum occurs, then using an
exponential shape would be the best choice. On the
other hand, if you wanted a signal that responds to
loud and quite signals with relative equality, a
logarithmic shape would be the better option.
Page of19 24
Figure 8: Blue is audio fed into Follow jack. Magenta is
ENV output with linear shape; orange is expo shape;
green is log shape.

Creating ADSR Envelopes
ADSR Envelope
An ADSR (attack-decay-sustain-release) envelope is like
an ASR envelope, except that it adds a fourth stage
known as “decay” after the attack stage. After hitting the
peak, an ADSR envelope “decays” to a sustain level less
than the peak level. See Figure 9.This sustain level and
the speed at which the envelope decays are controllable.
We can generate an ADSR envelope with the Shaped
Dual EnvVCA by feeding a gate into both Trig jacks. The
gate should be generated by an external module such as
a keyboard or sequencer that lets you control the pulse
width. The pulse width determines the length of the
sustain, that is, the ADSR envelope will do the attack and
decay segments and then hold at the sustain level until
the gate goes low. At that point it’ll do the release
segment.
Use a mult or stackable cable to patch the gate signal into both Trig jacks. Flip Channel A’s Trig switch
to AR, and Channel B to ASR. Both Cycle buttons should be off.
Set all Rise/Fall switches to Med. Channel A’s Rise will control the attack time, set it to Fast to start.
Set Channel B’s Rise to match Channel A’s: in order to produce a true ADSR envelope both Rise
sliders must always be set the same. Channel A’s Fall will control the release time, start with it a few
marks above Fast. Channel B’s Fall will control the decay time, start with it around the center position.
Page of20 24
Figure 9: ADSR. Ch B Level knob turned down in
2nd envelope to lower sustain level. Ch A Fall
slider moved up in third envelope to make decay
slower.
Cycle
AR
ASR
Cycle
AR
ASR
Rise Fall
Shaped Dual EnvVCA
TimeTime
Follow
VCA CVVCA CV
In
Audio BAudio A
Out
In
Out Lin 5VLin 5V
OR
Shape
Rise Fall
Slow
Fast
Med
Slow
Fast
Trig Cycle
Offset
Level
EOF
Fall
Rise
Shape Shape
Follow
ENV A ENV B
Shape
FallRise
Slow
Fast
Med
Slow
Fast
Trig
Cycle
Offset
Level
EOR A
Cycle off
Rise adjusts
attack. Set Ch A
and B Rise the
same.
Ch A Fall adjusts
release time.
Ch B Fall adjusts
decay time.
To mixer/output
amp
From sound
source
Channel B Level
controls sustain
level. Keep
between 12:00
and 2:30
Level at 2:30
Offset at 12:00
Gate (pulse width
controls sustain
period)
Cycle off
Rise and Fall
switches to Med
Trig set to ASR
Offset at center.